Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Postmortem examination of the lungs of a patient with advanced AIDS who had developed pulmonary arterial hypertension late in the course of the illness demonstrated extensive cytomegalovirus (CMV) infection in endothelial cells of the lung microvasculature. Enlarged CMV-infected endothelial cells were present in virtually all histologic sections of the lungs, protruded into and compromised the lumens of the small vessels they lined, and were estimated by image cytometry of immunohistochemically stained sections to comprise 0.8% of the total lung tissue volume. Comparison with experimental microvascular embolization studies suggests that this amount of compromise of the microvascular luminal area of the lung is sufficient to elevate pulmonary arterial pressure significantly. Pathologic features in this case differed from both the plexogenic arteriopathy seen in previously reported cases of AIDS-associated primary pulmonary hypertension and the usual form of CMV pneumonitis in AIDS in which alveolar epithelial cells are the predominant site of infection.
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PMID:Microvascular cytomegalovirus endothelialitis of the lung: a possible cause of secondary pulmonary hypertension in a patient with AIDS. 967 94

Prostacyclin (or epoprostenol), an arachidonic acid metabolite, is an effective treatment for patients with primary pulmonary hypertension. Interruption of chronic prostacyclin infusion can result in recurrent symptoms of dyspnea and fatigue. The etiology of this phenomenon is unknown. We hypothesized that sympathoadrenal activation could lead to increased vascular tone after abrupt termination of the infusion. To evaluate this effect, we monitored six chronically instrumented, awake sheep during and after infusion of prostacyclin. Prostacyclin decreased mean arterial pressure (MAP) by 14% and increased cardiac output by 33%. After the infusion ceased, MAP rebounded 23% above baseline, and cardiac output decreased by 28% from peak values within 10 min. We were unable to demonstrate an increase in norepinephrine levels after cessation of prostacyclin, nor did alpha-adrenergic blockade affect postinfusion hemodynamics. However, plasma renin activity increased >10-fold at peak infusion and remained elevated for up to 2 h after discontinuation of prostacyclin. Coinfusion of the angiotensin II-receptor antagonist L-158,809 resulted in complete abrogation of the postcessation rise in MAP. We conclude that renin-angiotensin system activation is primarily responsible for systemic hypertension occurring after abrupt cessation of prostacyclin infusion in sheep and that angiotensin II receptor blockade prevents this response. Our data do not support a role for sympathetic nervous system activation in the systemic pressor response after prostacyclin infusion.
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PMID:Angiotensin II mediates systemic rebound hypertension after cessation of prostacyclin infusion in sheep. 968 53

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease resulting from the thromboembolic obstruction of the segmental and/or large size pulmonary arteries, subsequently leading to pulmonary arterial hypertension. Incomplete resolution of acute pulmonary emboli and thrombus organization are believed to be important for the development of the disease. Primary pulmonary hypertension (PPH) is a further disease that at present is poorly understood but shows a clinical picture similar to CTEPH. Since lipoprotein(a) [Lp(a)]. a genetically determined risk factor for atherosclerosis and thrombosis, has been found increased in plasma of patients with deep vein thrombosis and pulmonary embolism, we measured plasma Lp(a) levels in 40 patients with CTEPH and 50 patients with PPH and compared them to 50 matched controls. The median for Lp(a) plasma levels was significantly higher in CTEPH patients (26.6 mg/dl) than in PPH patients (9.6 mg/dl) and controls (7.2 mg/dl). Increased plasma Lp(a) could, therefore. play a significant role in the mechanisms of ongoing thrombosis and thrombus organization in CTEPH, while its possible role in PPH can be limited to a small number of patients.
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PMID:Plasma Lp(a) levels are increased in patients with chronic thromboembolic pulmonary hypertension. 971 43

Endothelins (ETs) are 21-amino-acid peptides produced in many cells and tissues. The vascular ET system is represented mainly by ET-1 produced in endothelial cells. PreproET-1 gene expression is regulated by transactivating signals dependent on cooperative interaction of GATA-2 and AP-1 sites. ProET-1 is acted on by a furin-like enzyme to generate big ET-1, a 38-39-amino-acid peptide, which is converted to the mature 21-amino-acid peptide ET-1 by ET-converting enzyme (ECE) in endothelial cells, both intracellularly and on the cell membrane, and on the surface of underlying smooth muscle cells. The mature peptide ET-1 acts in a paracrine manner on smooth muscle cell ET(A) and ET(B) receptors to induce contraction and growth, and in an autocrine or paracrine manner on endothelial cells to induce production of the vasorelaxant and growth-inhibitory agents nitric oxide (NO) and prostacyclin. ET receptors are G-protein-coupled, resulting in activation of phospholipase C and generation of two second messengers, inositol triphosphate and diacylglycerol, which respectively stimulate calcium release and protein kinase C activation. Phospholipase D activation with generation of diacylglycerol, phospholipase A2 stimulation with release of arachidonic acid, activation of the Na+/H+ exchanger, and activation of tyrosine kinases and MAP kinases, are other pathways that contribute to contraction and growth induced by ET receptor stimulation. ET receptors may be downregulated by ET, especially under conditions in which large amounts of ET are being produced in the vasculature. This has been demonstrated in some models of experimental hypertension and in some forms of human hypertension. Some of the effects of angiotensin II, particularly growth of the smooth muscle media of blood vessels, have been shown under some conditions to be mediated by ET-1 via ET(A) receptors. Many ET-induced effects on smooth muscle cells can be blocked by ET(A)-selective ET antagonists, which makes possible an identification of the physiologic and pathophysiologic roles of the ET system in cardiovascular diseases such as hypertension, heart failure, atherosclerosis, coronary heart disease, restenosis after angioplasty, primary pulmonary hypertension, and other pathologic conditions.
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PMID:Vascular biology of endothelin. 988 41

The endothelins (ET) are potent 21-amino-acid vasoconstrictor peptides produced in many different tissues, particularly in the endothelium of blood vessels. ET-1 is the main endothelin secreted by the endothelium, and acts in a paracrine or autocrine fashion on blood vessels by interacting with ETA or ETB receptors on smooth muscle to stimulate contraction or on ETB receptors on endothelial cells to induce the release of vasorelaxants (nitric oxide and prostacyclin). Production of ET-1 is enhanced in several experimental models of hypertension in the rat, such as sodium-sensitive forms, e.g. deoxycorticosterone acetate (DOCA)-salt hypertensive, DOCA-salt-treated spontaneously hypertensive rats (SHR) and Dahl salt-sensitive rats, as well as other models such as stroke-prone SHR, angiotensin II-infused rats and fructose-fed rats, and possibly 1-K 1C Goldblatt hypertensive rats. In contrast, SHR, 2-K 1C Goldblatt hypertensive rats and nitric oxide-deficient (L-NAME-treated) hypertensive rats do not exhibit an ET-1 component. Endothelin dependency is manifested by excessive vascular growth, particularly in small arteries, and blood pressure lowering and regression of vascular growth after treatment with endothelin antagonists. The latter may be combined ETA/ETB or selective ETA antagonists, of which several are orally active and already in clinical development. In humans, endothelin-dependent vascular tone has been shown in studies of forearm blood flow. Enhanced expression of ET-1 mRNA has been demonstrated in the endothelium of small arteries of patients with moderate to severe hypertension. In a 4-week trial the combined ETA/ETB antagonist bosentan reduced the blood pressure of essential hypertensive patients equally to enalapril. Bosentan improved hemodynamics in patients with heart failure in acute and 2-week-long studies. Endothelin antagonists also offer promise in a rapidly fatal condition, primary pulmonary hypertension. Thus, the endothelin system appears to be involved in different forms of cardiovascular disease in experimental animals and humans, and its interruption offers great promise as a new therapeutic intervention in hypertension, heart failure and other diseases.
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PMID:Endothelin and endothelin antagonists in hypertension. 988 74

Phentermine and fenfluramine are widely used in the treatment of obesity. Despite the fact that primary pulmonary hypertension and mitral valve insufficiency have been associated with fenfluramine use, many of these patients need medication to achieve weight loss. Small degrees of weight loss have been shown to significantly improve obesity-related medical conditions such as hypertension, hypercholesterolemia, and noninsulin-dependent diabetes mellitus. Current practice is to give phentermine and fenfluramine in the morning and afternoon. Doses for phentermine have ranged from 15 to 37.5 mg and for fenfluramine from 20 to 120 mg per day. We report five cases of severely obese women with medical complications who were treated with phentermine 8 mg twice per day (at 1:00 p.m. and 4:00 p.m.) and fenfluramine 20 mg per day (at 4:00 p.m.). Because many obese patients skip breakfast and eat more in the afternoon and evening, medication was dosed in order to cover these high-risk eating periods. Overall, these patients lost a mean of 22.4% of their initial weight (range 18.6% to 32.8%) over an average of 8.4 months (range 3.5 to 16 months). These cases suggest that short-term weight loss can be achieved with a low dose of fenfluramine when both medications are given in the afternoon to better target the eating patterns of obese subjects.
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PMID:Lower dosages of phentermine-fenfluramine given in the afternoon: five cases with significant weight loss. 1020 59

Patients with end-stage liver failure, portal hypertension, and associated pulmonary artery hypertension (portopulmonary hypertension [PPHTN]) have a high mortality when undergoing liver transplantation. Successful transplantation in these patients may depend on efforts to reduce pulmonary artery pressure (PAP). To this end, a number of centers are using a continuous intravenous (IV) infusion of epoprostenol, which has been shown to improve symptoms, extend life span, and reduce PAP in patients with primary pulmonary hypertension. We report four cases in which treatment of patients with PPHTN with continuous IV epoprostenol was followed by the development of progressive splenomegaly, with worsening thrombocytopenia and leukopenia. This finding may limit the usefulness of epoprostenol in PPHTN and influence the timing of transplantation in such patients.
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PMID:Progressive splenomegaly after epoprostenol therapy in portopulmonary hypertension. 1047 35

Pulmonary artery hypertension in association with liver failure (portopulmonary hypertension [PPHTN]) is a significant barrier to liver transplantation because patients with this condition have a very high mortality when transplantation is undertaken. Inhaled nitric oxide (NO), a potent pulmonary vasodilator, reduces pulmonary artery pressure (PAP) in some patients with primary pulmonary hypertension, but its effect in patients with PPHTN is controversial. We investigated the hemodynamic effects of inhaled NO in 6 patients with PPHTN. Five of 6 patients responded to NO inhalation with decreases in PAP and pulmonary vascular resistance of greater than 10%; these decreases were statistically significant at NO concentrations of 10 and 30 ppm. Cardiac output did not significantly change. We conclude that inhalation of NO reduces PAPs in some patients with PPHTN.
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PMID:Inhaled nitric oxide reduces pulmonary artery pressures in portopulmonary hypertension. 1047 39

The pathogenesis of pulmonary veno-occlusive disease (PVOD) is not known. The diagnosis of PVOD frequently relies on its histological changes since it is often difficult to distinguish clinically from primary pulmonary hypertension. This study carried out a systematic analysis of the pulmonary venous and arterial remodelling that occurs in PVOD (n=5) and compared these changes to two other diseases affecting the pulmonary veins, mitral stenosis (MS; n=6) and fibrosing mediastinitis (FM; n=2), using established morphometric techniques. In PVOD, pronounced intimal and adventitial thickening were noted in veins of all sizes and arterialization of veins >50 microm external diameter was found. Similar changes were evident in the arterial wall, but intimal thickening was less severe than in the veins and medial thickening was more pronounced in arteries <300 microm external diameter. Eccentric intimal fibrosis of the veins was also noted for the first time in PVOD, although this feature occurred less frequently (approximately one third) than in MS. Less pronounced structural remodelling was also encountered in the veins in cases of MS and FM. The severity of the venous changes in PVOD may aid its diagnosis and lend insight into its pathogenesis. However, the similarity of the vascular changes in each form of venous hypertension also suggests that pathology alone may not always differentiate between these disease states. The similarity of the vascular changes in the three forms of venous hypertension suggests that, as in pulmonary artery hypertension, pressure, per se, is one of the triggers to vascular remodelling.
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PMID:Venous and arterial changes in pulmonary veno-occlusive disease, mitral stenosis and fibrosing mediastinitis. 1067 31

Pulmonary hypertension is the hemodynamic consequence of vascular changes within the precapillary (arterial) or postcapillary (venous) pulmonary circulation. These changes may be idiopathic, as in primary pulmonary hypertension or pulmonary veno-occlusive disease, but more commonly they represent a secondary response to alterations in pulmonary blood flow. The pulmonary and systemic bronchial circulations form broad anastomoses that largely prevent infarction except in settings of markedly elevated pulmonary venous pressure, underlying malignancy, or excessive embolic burden. Causes of precapillary pulmonary hypertension include long-standing cardiac left-to-right shunt, chronic thromboembolic disease, and widespread pulmonary embolism arising from intravascular malignant cells, parasites, or foreign materials. The classic radiologic features of precapillary pulmonary hypertension are central arterial enlargement, sharply pruned peripheral vascularity, and right-sided heart hypertrophy and chamber dilatation. Postcapillary pulmonary hypertension may develop secondary to focal venous constriction or to compromised pulmonary venous drainage due to left atrial neoplasia, mitral stenosis, or left ventricular failure. Radiologic manifestations of postcapillary pulmonary hypertension include prominent septal lines, small pleural effusions, and occasionally air-space opacities. In addition, radiologic evaluation of postcapillary pulmonary hypertension may demonstrate evidence of pulmonary arterial hypertension, secondary to the retrograde transmission of elevated pulmonary venous pressure across the capillary bed.
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PMID:From the archives of the AFIP: pulmonary vasculature: hypertension and infarction. 1071 47


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